A common problem associated with smoking articles such as cigarettes or cigars is the amount of sidestream smoke that is given off during static burning, for example when the smoking article is idling and not being drawn upon by the smoker or is simply resting in an ashtray while burning. Visible sidestream smoke that is given off by a smoking article such as a cigarette during static burning is irritating and objectionable to nonsmokers in the vicinity of the idling cigarette.
A problem with heretofor developed wrappers that produced low sidestream smoke has been that they give a flaky and/or off color ash due to poor ashing characteristics of the wrappers. Various mechanisms have been incorporated into smoking articles to reduce visible sidestream smoke and to improve the ashing characteristics of wrappers, but none to date has been commercially successful in overcoming both of these problems.
Probably the most effective means of reducing visible sidestream smoke, to date is disclosed and claimed in U.S. Pat. No. 3,231,377, Cline et al owned by applicant's assignee, Olin Corporation.
In this patent there is disclosed a wrapper for smoking articles such as cigarettes, cigars and the like containing at least 15% by weight magnesium oxide or its hydrate and at least 0.5% by weight of specific chemical adjuvant such as the alkali metal acetates, carbonates, citrates, nitrates or tartrates. The combination of magnesium oxide or its hydrate with any of the chemical adjuvants significantly reduces visible sidestream smoke that emanates during static burning from smoking articles employing the wrapper. The wrapper may comprise conventional cigarette paper with magnesium oxide and the adjuvant incorporated therein as the filler in the paper furnish or either or both of the additives may be applied to the paper as a coating. Wrappers containing the additives can be used in place of conventional wrappers for smoking articles or used as an inner wrapper for the tobacco column in combination with a conventional outer wrapping of cigarette paper or cigar wrap.
Following the teaching of this patent substantial and very desirable reduction in visible sidestream smoke can be achieved by using cigarette paper containing magnesium oxide as filler in combination with certain chemical adjuvants. These papers have consistently given a flaky ash and have been determined to be unacceptable for use by the cigarette manufacturers due to the poor ashing characteristics. Extensive testing has not identified any burning chemical or combination of burning chemicals which overcomes this problem.
Schur (in U.S. Pat. No. 2,733,720) discloses the use of minor amounts of asbestos fiber in certain cigarette papers to give more solid ash. These fibers would undoubtedly function to improve the ash from papers but are completely unacceptable for use in cigarettes in the light of present knowledge of inhalation hazards of asbestos. Similarly, Lamm (in U.S. Pat. Nos. 2,890,704 and 2,998,012) discloses cigarette wrappers made of interwoven glass fibers. It has been shown that glass fibers added to magnesium oxide paper give an acceptably solid ash. These, too, are unacceptable to the cigarette manufacturers.